Methods of fabricating polycrystalline diamond compacts

ABSTRACT

Embodiments of the invention relate to methods of fabricating a polycrystalline diamond compacts and applications for such polycrystalline diamond compacts. In an embodiment, a method of fabricating a polycrystalline diamond compact includes at least saturating a sintering aid material with non-diamond carbon to form a carbon-saturated sintering aid material and sintering a plurality of diamond particles in the presence of the carbon-saturated sintering aid particles to form a polycrystalline diamond table.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/323,138 filed on 12 Dec. 2011, which is a continuation-in-part ofU.S. application Ser. No. 12/394,356 filed on 27 Feb. 2009 (now U.S.Pat. No. 8,080,071 issued on 20 Dec. 2011), which claims the benefit ofU.S. Provisional Application No. 61/068,120 filed on 3 Mar. 2008, thecontents of each of the foregoing applications are incorporated herein,in their entirety, by this reference.

BACKGROUND

Wear-resistant, polycrystalline diamond compacts (“PDCs”) are utilizedin a variety of mechanical applications. For example, PDCs are used indrilling tools (e.g., cutting elements, gage trimmers, etc.), machiningequipment, bearing apparatuses, wire-drawing machinery, and in othermechanical apparatuses.

PDCs have found particular utility as superabrasive cutting elements inrotary drill bits, such as roller-cone drill bits and fixed-cutter drillbits. A PDC cutting element typically includes a superabrasive diamondlayer commonly known as a diamond table. The diamond table is formed andbonded to a substrate using a high-pressure/high-temperature (“HPHT”)process. The PDC cutting element may be brazed directly into a preformedpocket, socket, or other receptacle formed in a bit body. The substratemay often be brazed or otherwise joined to an attachment member, such asa cylindrical backing. A rotary drill bit typically includes a number ofPDC cutting elements affixed to the bit body. It is also known that astud carrying the PDC may be used as a PDC cutting element when mountedto a bit body of a rotary drill bit by press-fitting, brazing, orotherwise securing the stud into a receptacle formed in the bit body.

Conventional PDCs are normally fabricated by placing a cemented-carbidesubstrate into a container with a volume of diamond particles positionedon a surface of the cemented-carbide substrate. A number of suchcontainers may be loaded into an HPHT press. The substrate(s) andvolume(s) of diamond particles are then processed under HPHT conditionsin the presence of a catalyst material that causes the diamond particlesto bond to one another to form a matrix of bonded diamond grainsdefining a polycrystalline diamond (“PCD”) table. The catalyst materialis often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloysthereof) that is used for promoting intergrowth of the diamondparticles.

In one conventional approach, a constituent of the cemented-carbidesubstrate, such as cobalt from a cobalt-cemented tungsten carbidesubstrate, liquefies and sweeps from a region adjacent to the volume ofdiamond particles into interstitial regions between the diamondparticles during the HPHT process. The cobalt acts as a catalyst topromote intergrowth between the diamond particles, which results information of a matrix of bonded diamond grains having diamond-to-diamondbonding therebetween, with interstitial regions between the bondeddiamond grains being occupied by the solvent catalyst.

The presence of the solvent catalyst in the PCD table is believed toreduce the thermal stability of the PCD table at elevated temperatures.For example, the difference in thermal expansion coefficient between thediamond grains and the solvent catalyst is believed to lead to chippingor cracking of the PCD table during drilling or cutting operations,which consequently can degrade the mechanical properties of the PCDtable or cause failure. Additionally, some of the diamond grains canundergo a chemical breakdown or back-conversion to graphite viainteraction with the solvent catalyst. At elevated high temperatures,portions of the diamond grains may transform to carbon monoxide, carbondioxide, graphite, or combinations thereof, causing degradation of themechanical properties of the PCD table. One conventional approach forimproving the thermal stability of PDCs is to at least partially removethe solvent catalyst from the PCD table of the PDC by acid leaching.

Despite the availability of a number of different PDCs, manufacturersand users of PDCs continue to seek PDCs that exhibit improved wearresistance and thermal stability.

SUMMARY

Embodiments of the invention relate to methods of fabricating PDCs andapplications for such PDCs. In an embodiment, a method of fabricating aPDC includes at least saturating a sintering aid material withnon-diamond carbon to form a carbon-saturated sintering aid material andsintering a plurality of diamond particles in the presence of thecarbon-saturated sintering aid material to form a PCD table.

Other embodiments include PCD elements and PDCs formed by theabove-described methods, and applications utilizing such PCD bodies andPDCs in various articles and apparatuses, such as rotary drill bits,bearing apparatuses, wire-drawing dies, machining equipment, and otherarticles and apparatuses.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the invention, whereinidentical reference numerals refer to identical elements or features indifferent views or embodiments shown in the drawings.

FIG. 1A is a cross-sectional view of an embodiment of a PDC precursorassembly including a mixture comprising a plurality of sintering aidparticles at least saturated with carbon and a plurality of diamondparticles positioned adjacent to a substrate.

FIG. 1B is a cross-sectional view of a PDC formed by HPHT processing ofthe PDC precursor assembly shown in FIG. 1A.

FIG. 1C is an isometric view of the PDC shown in FIG. 1B.

FIG. 1D is a cross-sectional view of the PDC shown in FIGS. 1B and 1C inwhich the PCD table has been leached to a selected depth according to anembodiment.

FIG. 2A is a cross-sectional view of an embodiment of a PDC precursorassembly including a mixture comprising a plurality of sintering aidparticles at least saturated with carbon, a plurality ofcarbon-saturated sintering aid particles coated with submicron diamondparticles, and a plurality of diamond particles positioned adjacent to asubstrate.

FIG. 2B is a cross-sectional view of a PDC formed by HPHT processing ofthe PDC precursor assembly shown in FIG. 2A.

FIG. 3A is a cross-sectional view of an embodiment of a PDC precursorassembly including at least one layer of a plurality of carbon-saturatedsintering aid particles disposed between at least one layer of aplurality of diamond particles and a substrate.

FIG. 3B is a cross-sectional view of a PDC formed by HPHT processing ofthe PDC precursor assembly shown in FIG. 3A.

FIGS. 4A-4F are cross-sectional views illustrating different stages invarious embodiments of a method for fabricating a PDC and the PDC soformed.

FIGS. 5A-5F are cross-sectional views illustrating different stages invarious embodiments of a method for fabricating a PDC and the PDC soformed.

FIGS. 6 and 7 are isometric and top elevation views, respectively, of anembodiment of a rotary drill bit that may employ one or more of thedisclosed PDC embodiments.

FIG. 8 is an isometric cut-away view of an embodiment of athrust-bearing apparatus that may utilize one or more of the disclosedPDC embodiments.

FIG. 9 is an isometric cut-away view of an embodiment of a radialbearing apparatus that may utilize one or more of the disclosed PDCembodiments.

DETAILED DESCRIPTION

Embodiments of the invention relate to PDCs comprising a PCD tablesintered using a sintering aid material that has been at least saturatedwith non-diamond carbon and/or infiltrated with an infiltrant that is atleast saturated with non-diamond carbon. HPHT sintering diamondparticles in the presence of a sintering aid that has been at leastsaturated and, in some cases, supersaturated with non-diamond carbon maypromote diamond growth during HPHT sintering and may result in improvedthermal stability and/or wear resistance of the PCD so formed. Thedisclosed PDCs herein may be used in a variety of applications, such asrotary drill bits, mining tools, drill bits, bearing apparatuses,wire-drawing dies, machining equipment, and other articles andapparatuses.

FIG. 1A is a cross-sectional view of an embodiment of a PDC precursorassembly 100 for forming a PCD body from a mixture 105 comprising aplurality of sintering aid particles at least saturated with carbon(i.e., carbon-saturated sintering aid particles) and a plurality ofdiamond particles. Such an assembly 100 may be HPHT processed to form aPCD table 106 (FIG. 1B) integrally formed with and bonded to a substrate102 (FIG. 1B). The plurality of sintering aid particles that are atleast saturated with non-diamond carbon may sometimes be referred toherein in the different embodiments as carbon-saturated sintering aidparticles and may be saturated or supersaturated with carbon at standardtemperature and pressure (i.e., 0° C. and 1 atmosphere). For example,when the sintering aid particles are saturated with non-diamond carbon,they may include carbon at about the solubility limit for carbon in theparticular sintering aid material at standard temperature and pressure(i.e., 0° C. and 1 atmosphere). As another example, when the sinteringaid particles are supersaturated with non-diamond carbon, they mayinclude carbon in excess of the solubility limit for carbon in theparticular sintering aid material at standard temperature and pressure(i.e., 0° C. and 1 atmosphere or above). As used herein, the phrases “atleast saturated with carbon,” “saturated with carbon,” and variantsthereof include materials that are supersaturated with carbon andmaterials that are saturated with carbon. For example, the carbonsupersaturated in the sintering aid material may have a concentration ofabout 5 atomic % to about 30 atomic %, such as about 10 atomic % toabout 20 atomic %, about 20 atomic % to about 30 atomic %, or about 18atomic % to about 25 atomic %.

According to one or more embodiments, the carbon-saturated sintering aidparticles may be formed by mechanically milling sintering aid particleswith a non-diamond carbon to mechanically alloy the sintering aidparticles with non-diamond carbon. For example, the non-diamond carbonmay be selected from amorphous carbon, lamp black carbon, graphiteparticles (e.g., carbon-12 graphite particles, carbon-graphiteparticles, or mixtures thereof), graphene, nanotubes, fullerenes,combinations of the foregoing, and the like, while the sintering aidmaterials from which the sintering aid particles are made may beselected from cobalt, nickel, iron, copper, aluminum, titanium,tungsten, niobium, zirconium, tantalum, boron, silicon, alloys of any ofthe foregoing materials, any other suitable metal and/or alloy, orcombinations of any of the foregoing sintering aid materials. Some ofthe foregoing metal and alloys may not be carbide formers that willpartially consume diamond particles during HPHT sintering, such ascopper and copper alloys. Some of the foregoing metal and alloys fromwhich the sintering aid particles may be made are common diamondcatalysts (e.g., cobalt, iron, and nickel). However, other ones of theforegoing metals and alloys (e.g., aluminum, copper, titanium, tungsten,boron, silicon, and alloys) from which the sintering aid particles maybe made are not typically known as solvent catalysts, but can facilitatediamond sintering when mechanically alloyed with selected amount(s) ofnon-diamond carbon. Accordingly, a particular sintering aid material mayor may not be a diamond catalyst depending on its composition andnature.

Mechanically alloying is a process in which a powder and/or aparticulate mixture is subjected to impacts by an impacting medium thatcause a multiplicity of deformations, particle weldings, and fracturinguntil the powder and/or particulate mixture is converted to anessentially uniform particulate product. While attritor mills andhorizontal ball mills may be used for mechanical alloying, other typesof mechanical milling apparatuses may be used to practice the variousembodiments disclosed herein.

The plurality of sintering aid particles and the non-diamond carbon aresubjected to mechanical milling (e.g., attritor and/or ball milling) tosuch an extent that the sintering aid particles are mechanically alloyedwith a selected concentration of carbon so that the sintering aidparticles become at least saturated with carbon, and in someembodiments, supersaturated with carbon at standard temperature andpressure (i.e., 0° C. and 1 atmosphere) or above. For example, themechanical milling of the plurality of sintering aid particles and thenon-diamond carbon may be performed for about 100 hours to about 1100hours, such as about 200 hours to about 500 hours or about 150 hours toabout 700 hours. In some embodiments, the milling may be carried out upto 2000 hours resulting in the formation of metastable phases of Ni—C,Co—C, Cu—C, Al—C, Fe—C, Ti—C, W—C, B—C, Si—C, among others. For example,in some embodiments, the supersaturated solid solubility of carbon incopper mechanically alloyed with carbon may be as high as 28.5 atomic %.The metallographic structure of these metastable phases may be observedby scanning electron microscopy (“SEM”) and transmission electronmicroscopy (“TEM”). TEM observation of the effects of the millingprocess may reveal a structural change of the powders subjected to theball-milling process. For example, in an embodiment, the grain size maybe observed to decrease as mechanical alloy processing time isincreased.

In other embodiments, identification of the phases and measurement ofthe lattice constants may be achieved by mechanically slicing samples ofthe mechanically alloyed particles for analysis by X-ray diffractometry.In an embodiment, such analysis of nickel and non-diamond carbon revealsthe formation of a Ni—C supersaturated phase that may be observed withincreased milling time. For example, in an embodiment, the non-diamondcarbon concentration after approximately 1000 hours of mechanicalalloying nickel particles with carbon may be estimated to be about 9atomic % to about 12 atomic %.

Such carbon-saturated sintering aid materials present within the mixture105, shown in FIG. 1A, are believed to promote diamond growth betweendiamond particles during HPHT sintering so that the diamond-to-diamondbond density and/or quality increases. The increased diamond-to-diamondbond density present in the sintered PCD table 106 (FIG. 1B) is believedto increase the wear resistance and/or thermal stability as compared toa sintered PCD table fabricated without using carbon-saturated sinteringaid particles.

Referring again to FIG. 1A, the plurality of diamond particles may bemixed with the carbon-saturated sintering aid particles to form themixture 105. In some embodiments, the carbon-saturated sintering aidparticles may partially or substantially completely coat the diamondparticles. The plurality of diamond particles of the mixture 105 mayexhibit one or more selected sizes. The one or more selected sizes maybe determined, for example, by passing the diamond particles through oneor more sizing sieves or by any other method. In an embodiment, theplurality of diamond particles may include a relatively larger size andat least one relatively smaller size. As used herein, the phrases“relatively larger” and “relatively smaller” refer to particle sizesdetermined by any suitable method, which differ by at least a factor oftwo (e.g., 40 μm and 20 μm). More particularly, in various embodiments,the plurality of diamond particles may include a portion exhibiting arelatively larger size (e.g., 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm,40 μm, 30 μm, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm) and another portionexhibiting at least one relatively smaller size (e.g., 30 μm, 20 μm, 10μm, 15 μm, 12 μm, 10 μm, 8 μm, 4 μm, 2 μm, 1 μm, 0.5 μm, less than 0.5μm, 0.1 μm, less than 0.1 μm). In an embodiment, the plurality ofdiamond particles may include a portion exhibiting a relatively largersize between about 40 μm and about 15 μm and another portion exhibitinga relatively smaller size between about 12 μm and 2 μm. Of course, theplurality of diamond particles may also include three or more differentsizes (e.g., one relatively larger size and two or more relativelysmaller sizes) without limitation. The sintering aid particles mayexhibit any of the particle sizes and distributions discussed above forthe diamond particles.

It is noted that the as-sintered diamond grain size of the PCD table 106in FIG. 1B may differ from the average particle size of the plurality ofdiamond particles prior to sintering due to a variety of differentphysical processes, such as grain growth, diamond particles fracturing,carbon provided from another carbon source, or combinations of theforegoing.

FIGS. 1B and 1C are cross-sectional and isometric views, respectively,of a PDC 120 formed by HPHT processing of the PDC precursor assembly 100shown in FIG. 1A. The PDC 120 includes the PCD table 106 comprising asintering aid material from the plurality of sintering aid particlesthat are at least saturated with carbon. The PCD table 106 includes aworking upper surface 108, an interfacial surface 104, and at least onelateral surface 110 extending therebetween. Although the upper surface108 is illustrated as being substantially planar, the upper surface 108may have a nonplanar geometry, such as a convex or concave geometry.Furthermore, the PCD table 106 may include a chamfer 112 or other edgegeometry that extends about the upper surface 106. For example, thechamfer 112 may be formed by grinding, lapping, laser machining,electro-discharge machining, or combinations of the foregoing.Additionally, other regions of the PCD table 106 may also function as aworking region, such as the at least one lateral surface 110.

The substrate 102 (having any suitable geometry) of the PDC 120 isbonded to the interfacial surface 104 of the PCD table 106. Suitablematerials for the substrate 102 include cemented carbides, such astitanium carbide, niobium carbide, tantalum carbide, vanadium carbide,tungsten carbide, or combinations of any of the preceding carbidescemented with iron, nickel, cobalt, or alloys thereof. In an embodiment,the substrate 102 may comprise cobalt-cemented tungsten carbide.Although the interfacial surface 104 of the substrate 102 is illustratedas being substantially planar, the interfacial surface may exhibit aselected nonplanar geometry and the back surface 104 of the PCD table106 may exhibit a correspondingly configured geometry.

In order to efficiently sinter the mixture 105 of the plurality ofsintering aid particles at least saturated with carbon and the pluralityof diamond particles to form the PCD table 106 bonded to the substrate102, the PDC precursor assembly 100 may be enclosed in a pressuretransmitting medium, such as a refractory metal can, graphite structure,pyrophyllite, combinations thereof, or other suitable pressuretransmitting structure to form a cell assembly. Examples of suitablegasket materials and cell structures for use in manufacturing PCD aredisclosed in U.S. Pat. No. 6,338,754 and U.S. patent application Ser.No. 11/545,929, each of which is incorporated herein, in its entirety,by this reference. Another example of a suitable pressure transmittingmaterial is pyrophyllite, which is commercially available fromWonderstone Ltd. of South Africa. The cell assembly, including thepressure transmitting medium, the mixture 105 of a plurality ofsintering aid particles at least saturated with carbon and a pluralityof diamond particles, and the substrate 102 is subjected to an HPHTprocess using an ultra-high pressure press at a temperature of at leastabout 1000° C. (e.g., about 1100° C. to about 2200° C., or about 1200°C. to about 1450° C.) and a pressure in the pressure transmitting mediumof at least about 7.5 GPa (e.g., about 7.5 GPa to about 15 GPa) for atime sufficient to sinter the diamond particles together and form thePCD table 106 comprising directly bonded-together diamond grains. Forexample, the pressure in the pressure transmitting medium employed inthe HPHT process may be at least about 8.0 GPa, at least about 9.0 GPa,at least about 10.0 GPa, at least about 11.0 GPa, at least about 12.0GPa, or at least about 14 GPa. Further details about HPHT processingtechniques that may be used to practice the embodiments disclosed hereinare disclosed in U.S. Pat. No. 7,866,418, which is incorporated herein,in its entirety, by reference.

The pressure values employed in the HPHT processes disclosed hereinrefer to the pressure in the pressure transmitting medium at roomtemperature (e.g., about 25° C.) with application of pressure using anultra-high pressure press and not the pressure applied to the exteriorof the cell assembly. The actual pressure in the pressure transmittingmedium at sintering temperature may be higher. The ultra-high pressurepress may be calibrated at room temperature by embedding at least onecalibration material that changes structure at a known pressure, such asPbTe, thallium, barium, or bismuth in the pressure transmitting medium.Further, optionally, a change in resistance may be measured across theat least one calibration material due to a phase change thereof. Forexample, PbTe exhibits a phase change at room temperature at about 6.0GPa and bismuth exhibits a phase change at room temperature at about 7.7GPa. Examples of suitable pressure calibration techniques are disclosedin G. Rousse, S. Klotz, A. M. Saitta, J. Rodriguez-Carvajal, M. I.McMahon, B. Couzinet, and M. Mezouar, “Structure of the IntermediatePhase of PbTe at High Pressure,” Physical Review B: Condensed Matter andMaterials Physics, 71, 224116 (2005) and D. L. Decker, W. A. Bassett, L.Merrill, H. T. Hall, and J. D. Barnett, “High-Pressure Calibration: ACritical Review,” J. Phys. Chem. Ref. Data, 1, 3 (1972).

During the HPHT process, the carbon-saturated sintering aid particleswithin the mixture 105 may at least partially melt during HPHTprocessing to facilitate diamond growth. Due to the additional carbonfrom the at least partially melted carbon-saturated sintering aidmaterial, additional diamond may be grown between the diamond particlesso that the diamond-diamond bond density increases. The PCD table 106so-formed includes directly bonded-together diamond grains exhibitingdiamond-to-diamond bonding (e.g., sp³ bonding) therebetween. Theplurality of bonded diamond grains defines a plurality of interstitialregions. While most of the interstitial regions include sintering aidmaterial provided from the carbon-saturated sintering aid particles,some of the interstitial regions near the substrate 102 may include acatalyst material disposed therein infiltrated from the substrate 102,such as iron, nickel, cobalt, or alloys thereof. The catalyst materialinfiltrated from the substrate 102 helps metallurgically bond the PCDtable 106 so formed to the substrate 102. In some embodiments, thesintering aid material within the interstitial regions of the PCD table106 may still be at least saturated with carbon at standard temperatureand pressure (i.e., 0° C. and 1 atmosphere). In other embodiments, thesintering aid material within the interstitial regions may still evenremain supersaturated with carbon at standard temperature and pressure(i.e., 0° C. and 1 atmosphere). In some embodiments, thecarbon-saturated sintering aid material present in the PCD table 106 mayinclude one or more of carbon fibrules, carbon onions, C-12, C-13,graphite, other sp²-carbon phases, metal carbide phases thereincharacteristic of the sintering aid material being at least saturatedwith carbon, or combinations thereof.

In embodiments in which at least a portion of the sintering aid materialin the PCD table 106 is at least saturated with carbon, thecarbon-saturated sintering aid material has less of a tendency todissolve carbon therein at elevated temperatures. Therefore, at elevatedtemperatures commonly experienced during drilling when the PDC 120 isemployed as a cutting element of a rotary drill bit, thecarbon-saturated sintering aid material in the PCD table 106 does notsignificantly facilitate back conversion of the diamond grains tographite and/or another by-product. For example, it is currentlybelieved by the inventors that absent the sintering aid material beingat least saturated with carbon, carbon from the diamond grains may bedissolved in the sintering aid material and precipitated as graphiteunder the non-diamond stable conditions typically experienced duringdrilling operations.

FIG. 2A is a cross-sectional view of an embodiment of a PDC precursorassembly 200 including a mixture 202 comprising: (i) a plurality ofsintering aid particles at least saturated with carbon 208, a pluralityof carbon-saturated sintering aid particles coated with submicrondiamond particles 210, or combinations thereof, (ii) and a plurality ofdiamond particles 212 positioned adjacent to a substrate 102. In thisembodiment, a plurality of submicron diamond particles may be mixed witha plurality of sintering aid particles and non-diamond carbon and besubjected to any of the mechanical milling processes disclosed herein.The product from such mechanical alloying may result in the plurality ofcarbon-saturated sintering aid particles coated and/or embedded withsubmicron diamond particles 210.

The plurality of submicron diamond particles may exhibit one or moreselected submicron sizes. The one or more submicron selected sizes maybe determined, for example, by passing the diamond particles through oneor more sizing sieves or by any other method. In an embodiment, theplurality of submicron diamond particles may include a relatively largersize and at least one relatively smaller size. As used herein, thephrases “relatively larger” and “relatively smaller” refer to particlesizes determined by any suitable method, which differ by at least afactor of two (e.g., 40 nm and 20 nm). More particularly, in variousembodiments, the plurality of submicron diamond particles may include aportion exhibiting a relatively larger size (e.g., 900 nm, 800 nm, 700nm, 600 nm, 500 nm, 400 nm, 300 nm, 200 nm, 150 nm, 120 nm, 100 nm, 80nm) and another portion exhibiting at least one relatively smaller size(e.g., 450 nm, 400 nm, 350 nm, 300 nm, 250 nm, 200 nm, 150 nm, 100 nm,75 nm, 60 nm, 50 nm, 40 nm, 20 nm, 10 nm, 8 nm, 2 nm, 1 nm, 0.5 nm, lessthan 0.5 nm, 0.1 nm, less than 0.1 nm). In an embodiment, the pluralityof submicron diamond particles may include a portion exhibiting arelatively larger size between about 400 nm and about 150 nm and anotherportion exhibiting a relatively smaller size between about 12 nm and 2nm. Of course, the plurality of submicron diamond particles may alsoinclude three or more different sizes (e.g., one relatively larger sizeand two or more relatively smaller sizes), without limitation.

FIG. 2B is a cross-sectional view of a PDC 220 formed by HPHT processingof the PDC precursor assembly 200 shown in FIG. 2A using any of the HPHTconditions disclosed herein. The PDC 220 comprises a PCD table 222 thatincludes a working upper surface 224 and an interfacial surface 226bonded to the substrate 102. The PCD table 222 includes a plurality ofdirectly bonded-together diamond grains exhibiting diamond-to-diamondbonding therebetween (e.g., sp³ bonding) defining a plurality ofinterstitial regions.

The interstitial regions of the PCD table 222 may include a sinteringaid material disposed therein provided from the plurality of sinteringaid particles 208 that were at least saturated with carbon and/or asintering aid material provided from the plurality of carbon-saturatedsintering aid particles coated with submicron diamond particles 210present in the mixture 202 of the PDC precursor assembly 200 in FIG. 2A.Catalyst material from the substrate 102 may also infiltrate into themixture 202 during HPHT processing (e.g., cobalt from a cobalt-cementedtungsten carbide substrate) to occupy some of the interstitial regionsadjacent to the substrate 102, which helps metallurgically bond the PCDtable 222 to the substrate 102. In some embodiments, the sintering aidmaterial within the interstitial regions of the PCD table 222 may be atleast saturated or even supersaturated with carbon at standardtemperature and pressure (i.e., 0° C. and 1 atmosphere). For example,the sintering aid material located in the interstitial regions of thePCD table 106 may be at least saturated with carbon and, in someembodiments, supersaturated with carbon for temperature and pressureconditions typically experienced during subterranean drillingoperations. In some embodiments, the carbon-saturated sintering aidmaterial may include one or more of carbon fibrules, carbon onions,carbon-12, carbon-13, graphite, other sp²-carbon phases, metal carbidephases therein characteristic of the sintering aid material being atleast saturated with carbon, or combinations thereof. It is believedthat the presence of the carbon-saturated sintering aid material mayprovide the ability to offer more carbon during sintering and promoteextra diamond-to-diamond bonding growth resulting in an increase of thediamond-to-diamond bond density and/or quality.

In another embodiment, the mixture 202 may be formed into a green bodyand positioned adjacent to the substrate 102, and subjected to HPHTprocessing to form the PDC 220. A green body may assist withmanufacturing and handling of the mixture 202 because a suitablesacrificial binder (e.g., a wax or polymer binder) is added to themixture 202 that binds the particles together.

FIG. 3A is a cross-sectional view of an embodiment of a PDC precursorassembly 300 including at least one layer of a plurality ofcarbon-saturated sintering aid particles 304 positioned between at leastone layer of a plurality of diamond particles 302 and a substrate 102.The plurality of carbon-saturated sintering aid particles within theregion 304 may be fabricated employing any of the mechanical alloyingprocesses disclosed herein in conjunction with any of the sintering aidmaterials discussed herein. Similarly, the plurality of diamondparticles may exhibit any of the size distributions previouslydiscussed. In another embodiment, the at least one layer of theplurality of diamond particles 302 may be disposed between the substrate102 and the at least one layer of the plurality of carbon-saturatedsintering aid particles 304.

FIG. 3B is a cross-sectional view of a PDC 320 formed by HPHT processingof the PDC precursor assembly 300 shown in FIG. 3A using any of the HPHTconditions disclosed herein. The PDC 320 comprises a PCD table 322 thatincludes an upper surface 324 and an interfacial surface 326 bonded tothe substrate 102. The PCD table 322 includes a plurality of directlybonded-together diamond grains exhibiting diamond-to-diamond bondingtherebetween (e.g., sp³ bonding) defining a plurality of interstitialregions.

During HPHT processing, the sintering aid material from the layer 304 atleast partially melts and infiltrates into the plurality of diamondparticles of the layer 302 to facilitate formation of the PCD table 322from the diamond particles and promotes diamond growth. As with otherembodiments, the sintering aid material located in the interstitialregions of the PCD table 322 may be provided from the plurality ofcarbon-saturated sintering aid particles that are at least saturatedwith carbon. For example, after HPHT processing, the sintering aidmaterial may still be at least saturated or even still supersaturated.Catalyst material from the substrate 102 may also infiltrate into thediamond particles during HPHT processing (e.g., cobalt from acobalt-cemented tungsten carbide substrate) to occupy some of theinterstitial regions (e.g., adjacent to the substrate 102), which mayhelp metallurgically bond the PCD table 322 to the substrate 102.

FIGS. 4A-4F are cross-sectional views illustrating a method offabricating a PDC according to an embodiment that comprises forming aPCD table from a plurality of sintering aid particles at least saturatedwith carbon and a plurality of diamond particles in a first HPHT processfollowed by at least partially leaching the so-formed PCD table. A PDCis subsequently formed by bonding the at least partially leached PCDtable to a substrate in a second HPHT process.

FIG. 4A illustrates a PDC precursor assembly 400 including a mixture 402comprising a plurality of carbon-saturated sintering aid particles mixedwith a plurality of diamond particles assembled with a substrate 102.The plurality of carbon-saturated sintering aid particles may befabricated employing any of the mechanical alloying processes and any ofthe sintering aid materials discussed herein. Similarly, the pluralityof diamond particles may be of any of the size distributions previouslydiscussed.

Referring to FIG. 4B, a PDC 410 is formed by the HPHT processing of thePDC precursor assembly 400 shown in FIG. 4A using any of the HPHTconditions disclosed herein. The PDC 410 comprises a PCD table 412 thatincludes an upper surface 414, an optional chamfer 418, and aninterfacial surface 416 bonded to the substrate 102. The PCD table 412includes a plurality of directly bonded-together diamond grainsexhibiting diamond-to-diamond bonding therebetween (e.g., sp³ bonding)defining a plurality of interstitial regions.

During HPHT processing, the sintering aid material from the plurality ofcarbon-saturated sintering aid particles facilitate formation of the PCDtable 412 from the plurality of diamond particles and promotes diamondgrowth as previously discussed. As with other embodiments, the sinteringaid material located in the interstitial regions of the PCD table 412 soformed may be provided from the plurality of carbon-saturated sinteringaid particles. For example, the sintering aid material may still be atleast saturated or even still supersaturated after HPHT processing.Catalyst material from the substrate 102 may also infiltrate into themixture 402 during HPHT processing (e.g., cobalt from a cobalt-cementedtungsten carbide substrate) to occupy some of the interstitial regionsadjacent to the substrate 102, which helps metallurgically bond the PCDtable 412 to the substrate 102.

The PCD table 412, shown in FIG. 4B, may be separated from the substrate102 using a grinding process, wire-electrical-discharge machining (“wireEDM”), combinations thereof, or another suitable material-removalprocess. FIG. 4C shows the separated PCD table 422. The separated PCDtable 422 may be leached by immersion in an acid, such as aqua-regia,nitric acid, hydrofluoric acid, or subjected to another suitable processto remove at least a portion of the catalyst material andcarbon-saturated sintering aid material from the interstitial regions ofthe separated PCD table 422 and form an at least partially leached PCDtable 432 as shown in FIG. 4D. For example, the separated PCD table 422may be immersed in the acid for about 2 to about 7 days (e.g., about 3,5, or 7 days) or for a few weeks (e.g., about 4 weeks) depending on theprocess employed. In other embodiments, the PCD table 412 may not beformed on the substrate 102, thereby eliminating the need for removal ofthe substrate 102.

Referring to FIG. 4E, a PDC precursor assembly 440 may be formed bypositioning an additional substrate 102 adjacent to the at leastpartially leached PCD table 432. The at least partially leached PCDtable 432 includes a working surface 434 and an opposing interfacialsurface 436 positioned adjacent to the substrate 102. The at leastpartially leached PCD table 432 also includes a plurality ofinterstitial regions that were previously occupied by the sintering aidand/or catalyst material. These previously occupied interstitial regionsform a network of at least partially interconnected pores that extendbetween the working surface 434 and interfacial surface 436. Theassembly 440 may be subject to HPHT processing for a time sufficient tobond the at least partially leached PCD table 432 to the substrate 102and form a PDC 450 as shown in FIG. 4F.

The HPHT process bonds the at least partially leached PCD table 432 tothe substrate 102 and may cause a metallic infiltrant from the substrate102 or another source to infiltrate into the interstitial regions of theat least partially leached PCD table 432. The HPHT temperature may besufficient to melt at least one constituent of the substrate 102 (e.g.,cobalt, nickel, iron, alloys thereof, or another constituent) thatinfiltrates the at least partially leached PCD table 432. The PDC 450so-formed includes a PCD table 452 in which the interstitial regionsthereof are at least partially filled with the metallic infiltrant. Itis noted that the PDC 450 may exhibit other geometries than the geometryillustrated in FIG. 4F. For example, the PDC 450 may exhibit anon-cylindrical geometry. For example, the PCD table 452 may bechamfered, as illustrated, after HPHT processing. Optionally, the PDCtable 452 may be leached to at least partially remove the metallicinfiltrant.

FIGS. 5A-5F are cross-sectional views illustrating a method offabricating a PDC according to an embodiment that comprises forming aPCD table from a plurality of sintering aid particles at least saturatedwith carbon and a plurality of diamond particles in a first HPHT processand at least partially leaching the so-formed PCD table. The at leastpartially leached PCD table is then cleaned to remove at least some ofthe leaching by-products therein. A PDC is subsequently formed bypositioning a plurality of carbon-saturated sintering aid particlesbetween the at least partially leached PCD table and a substrate andbonding in a second HPHT process.

FIG. 5A illustrates an assembly 500 including a mixture 502 comprising aplurality of carbon-saturated sintering aid particles and a plurality ofdiamond particles. The plurality of carbon-saturated sintering aidparticles found in the mixture 502 may be fabricated using any of thesintering aid materials and mechanical alloying methods disclosedherein. Similarly, the plurality of diamond particles within the mixture502 may exhibit of any of the size distributions disclosed herein. Themixture 502 including the plurality of carbon-saturated sintering aidparticles and the plurality of diamond particles may be subjected toHPHT processing to form the PCD table 512 shown in FIG. 5B using any ofthe HPHT conditions disclosed herein. The PCD table 512 comprises aworking surface 514 and an interfacial surface 518. The PCD table 512further includes a plurality of directly bonded-together diamond grainsexhibiting diamond-to-diamond bonding therebetween (e.g., sp³ bonding)defining a plurality of interstitial regions.

During HPHT processing, the sintering aid material from the plurality ofcarbon-saturated sintering aid particles facilitates formation of thePCD table 512 from the plurality of diamond particles and promotesdiamond growth as previously discussed. As with other embodiments, thesintering aid material located in the interstitial regions of the PCDtable 512 so formed may be provided from the plurality ofcarbon-saturated sintering aid particles. For example, the sintering aidmaterial may still be at least saturated or even still supersaturatedafter HPHT processing.

As shown in FIG. 5C, the as-sintered the PCD table 512 may be subject toleaching using any of the methods previously described to remove atleast a portion of the sintering aid material from the interstitialregions of the PCD table 512 and form an at least partially leached PCDtable 522 as shown in FIG. 5C.

As a result of the leaching process used to remove at least a portion ofthe sintering aid material, the at least partially leached PCD table 522shown in FIGS. 5B and 5C may include leaching by-products. For example,leaching agents used to remove, for example, cobalt from theinterstitial regions may leave one or more types of residual salts, oneor more types of oxides, combinations of the foregoing, or anotherleaching by-product within at least some of the interstitial regions ofthe at least partially leached PCD table 522. For example, dependingupon the chemistry of the leaching solution, the leaching by-productsmay comprise a salt of nitric acid, hydrochloric acid, phosphoric acid,acetic acid, or mixtures of the foregoing. For example, the salt may becobalt nitrate or cobalt chloride. The leaching by-products may alsocomprise a metal oxide (e.g., an oxide of tungsten, cobalt or othermetal) and/or another type of metal present in the sintering aid of theat least partially leached PCD table 522 prior to leaching. It iscurrently believed that such leaching by-products may block, obstruct,or otherwise inhibit infiltration of the at least partially leached PCDtable 522 with metallic infiltrant when the at least partially leachedPCD table 522 is attempted to be bonded to a substrate.

Referring to FIG. 5D, at least some of the leaching by-products may beremoved from the at least partially leached PCD table 522. For example,as shown in FIG. 5D, at least some of the leaching by-products may beremoved by subjecting the at least partially leached PCD table 522 to athermal-cleaning process. In such a thermal-cleaning process, the atleast partially leached PCD table 522 may be heated under partial vacuum(e.g., at a pressure less than ambient atmospheric pressure) to atemperature sufficient to sublimate at least some of the leachingby-products present in the at least partially leached PCD table 522, butbelow a temperature at which the diamond grains of the at leastpartially leached PCD table 522 may significantly degrade. For example,the at least partially leached PCD table 522 may be heated in a vacuumfurnace at a temperature between at least about 600° C. and less thanabout 700° C. for about 0.5 hours to about 2.0 hours or more. In anembodiment, the at least partially leached PCD table 522 may be heatedin a vacuum furnace at a temperature of about 650° C. for about 1 hourto about 1.5 hours.

In another embodiment, at least some of the leaching by-products may beremoved from the at least partially leached PCD table 522 using achemical cleaning process. For example, the at least partially leachedPCD table 522 may be immersed in hydrofluoric acid. The concentration ofthe hydrofluoric acid and the immersion time of the at least partiallyleached PCD table 522 in the hydrofluoric acid may be selected so thatat least some of the leaching by-products and, in some embodiments,substantially all of the leaching by-products may be removed from the atleast partially leached PCD table 522.

In an embodiment of a chemical cleaning process, at least some of theleaching by-products may be removed using an ultrasonic cleaningprocess. For example, the at least partially leached PCD table 522 ofFIG. 5C may be immersed in a selected solvent and ultrasonic energyapplied to the selected solvent for a selected period of time to effectremoval of at least some of the leaching by-products and, in someembodiments, substantially all of the leaching by-products may beremoved from the at least partially leached PCD table 522. The selectedsolvent may be an aqueous solution (e.g., hydrofluoric acid) or anorganic solvent.

Additional details about suitable cleaning techniques for removing theleaching by-products are disclosed in U.S. Pat. No. 7,845,438. U.S. Pat.No. 7,845,438 is incorporated herein, in its entirety, by thisreference.

In another embodiment, following removal of at least some of theleaching by-products, the interfacial surface 526 of the at leastpartially leached PCD table 522 may be bonded to a substrate in an HPHTbonding process to form a PDC in the same manner as the at leastpartially leached PCD table 432 was bonded to form the PDC 450 shown inFIGS. 4E and 4F. During the HPHT bonding process, the at least partiallyleached PCD table 522 may be infiltrated only with the metallicinfiltrant from the substrate, such as cobalt from a cobalt-cementedcarbide substrate.

Referring to FIG. 5E, an assembly 540 may be formed by positioning an atleast carbon-saturated infiltrant particle layer 544 between thesubstrate 102 and the at least partially leached and cleaned PCD table522. However, in other embodiments, the at least partially leached andcleaned PCD table 522 may be positioned between the substrate 102 andthe at least carbon-saturated infiltrant particle layer 544. Forexample, the at least carbon-saturated infiltrant particle layer 544includes carbon-saturated particles made from any of the foregoingsintering aid particles that have been at least saturated with carbon.For example, the carbon-saturated particles may be unbounded or in theform of a green body. However, depending upon the infiltrationconditions, composition, nature of the carbon-saturated particles, orcombinations thereof, the carbon-saturated particles may or may notfunction as a catalyst. The at least partially leached PCD table 522also includes a plurality of interstitial regions that were previouslyoccupied by a sintering aid material provided from the carbon-saturatedsintering aid particles within mixture 502 (shown in FIG. 5A) and form anetwork of at least partially interconnected pores that extend betweenthe working surface 524 and interfacial surface 526. The assembly 540may be subject to HPHT processing for a time sufficient to infiltrateand bond the at least partially leached and cleaned PCD table 522 to thesubstrate 102 and form a PDC 550 as shown in FIG. 5F. The HPHT processbonds the at least partially leached PCD table 522 to the substrate 102and may cause a metallic infiltrant from the substrate 102 and acarbon-saturated infiltrant from the carbon-saturated infiltrantparticles to infiltrate the interstitial regions of the at leastpartially leached PCD table 522. The PDC 550 so-formed includes a PCDtable 552 in which the interstitial regions thereof are at leastpartially filled with the infiltrant. At least some of the interstitialregions are occupied by infiltrant provided from the carbon-saturatedinfiltrant particles of the layer 544, while interstitial regions at ornear the substrate 102 may be occupied by the metallic infiltrant fromthe substrate 102. The infiltrant provided from the carbon-saturatedinfiltrant particles of the layer 544 may still be at least saturated oreven still supersaturated with carbon after HPHT processing. It iscurrently believed that when the infiltrant remains at leastsupersaturated after HPHT processing/infiltrant, the thermal stabilityof the PCD table 552 may be enhanced because back conversion of thediamond grains to graphite or other reaction product is reduced.

In some embodiments, the at least partially leached PCD table 522 may befabricated in a conventional manner. The conventionally fabricated atleast partially leached PCD table may then be attached to the substrate102 as shown and described in FIGS. 5E and 5F.

In any of the PDC embodiments disclosed herein, the PCD table may besubjected to a leaching process (e.g., an acid leaching process) to atleast partially remove the sintering aid material disposed in theinterstitial regions of the PCD table to a selected depth from one ormore of the upper working surface, the chamfer (if present), or the atleast one lateral surface. For example, according to an embodiment, FIG.1D is a cross-sectional view of the PDC 120 in which the PCD table 110has been leached to a selected depth “d” to form a leached region 122,with the unaffected underlying PCD table 106 labeled as region 124. Forexample, the selected depth “d” may be greater than about 50 μm, such asabout 50 μm to about 800 μm, about 200 μm to about 800 μm, about 400 μmto about 800 μm, or about 250 μm to about 500 μm.

FIG. 6 is an isometric view and FIG. 7 is a top elevation view of arotary drill bit 600 according to an embodiment. The rotary drill bit600 includes at least one PDC fabricating according to any of thepreviously described PDC embodiments. The rotary drill bit 600 comprisesa bit body 602 that includes radially and longitudinally extendingblades 604 with leading faces 606, and a threaded pin connection 608 forconnecting the bit body 602 to a drilling string. The bit body 602defines a leading end structure configured for drilling into asubterranean formation by rotation about a longitudinal axis 610 andapplication of weight-on-bit. At least one PDC cutting element,manufactured and configured according to any of the previously describedPDC embodiments (e.g., the PDC 120, 220, 320, 450, or 550), may beaffixed to rotary drill bit 600 by, for example, brazing, mechanicalaffixing, or another suitable technique. With reference to FIG. 6, eachof a plurality of PDCs 612 is secured to the blades 604. For example,each PDC 612 may include a PCD table 614 bonded to a substrate 616. Moregenerally, the PDCs 612 may comprise any PDC disclosed herein, withoutlimitation. In addition, if desired, in an embodiment, a number of thePDCs 612 may be conventional in construction. Also, circumferentiallyadjacent blades 604 define so-called junk slots 618 therebetween, asknown in the art. Additionally, the rotary drill bit 600 includes aplurality of nozzle cavities 620 for communicating drilling fluid fromthe interior of the rotary drill bit 600 to the PDCs 612.

FIGS. 6 and 7 merely depict one embodiment of a rotary drill bit thatemploys at least one cutting element comprising a PDC fabricated andstructured in accordance with the disclosed embodiments, withoutlimitation. The rotary drill bit 600 is used to represent any number ofearth-boring tools or drilling tools, including, for example, core bits,roller-cone bits, fixed-cutter bits, eccentric bits, bicenter bits,reamers, reamer wings, mining rotary drill bits, or any other downholetool including PDCs, without limitation. For example, the PDCs disclosedherein may be employed in roof bolt drill bits disclosed in U.S.Application Publication No. 2011/0284294 filed on 9 Mar. 2009, which isincorporated herein, in its entirety, by this reference.

The PDCs disclosed herein may also be utilized in applications otherthan rotary drill bits. For example, the disclosed PDC embodiments maybe used in thrust-bearing assemblies, radial bearing assemblies,wire-drawing dies, artificial joints, machining elements, and heatsinks.

FIG. 8 is an isometric cut-away view of a thrust-bearing apparatus 800according to an embodiment, which may utilize any of the disclosed PDCembodiments as bearing elements. The thrust-bearing apparatus 800includes respective thrust-bearing assemblies 802. Each thrust-bearingassembly 802 includes an annular support ring 804 that may be fabricatedfrom a material, such as carbon steel, stainless steel, or anothersuitable material. Each support ring 804 includes a plurality ofrecesses (not labeled) that receives a corresponding bearing element806. Each bearing element 806 may be mounted to a corresponding supportring 804 within a corresponding recess by brazing, press-fitting, usingfasteners, or another suitable mounting technique. One or more, or allof bearing elements 806 may be configured according to any of thedisclosed PDC embodiments. For example, each bearing element 806 mayinclude a substrate 808 and a PCD table 814, with the PCD table 814including a bearing surface 812.

In use, the bearing surfaces 812 of one of the thrust-bearing assemblies802 bears against the opposing bearing surfaces 812 of the other one ofthe bearing assemblies 802. For example, one of the thrust-bearingassemblies 802 may be operably coupled to a shaft to rotate therewithand may be termed a “rotor.” The other one of the thrust-bearingassemblies 802 may be held stationary and may be termed a “stator.”

FIG. 9 is an isometric cut-away view of a radial bearing apparatus 900according to an embodiment, which may utilize any of the disclosed PDCembodiments as bearing elements. The radial bearing apparatus 900includes an inner race 902 positioned generally within an outer race904. The outer race 904 includes a plurality of bearing elements 906affixed thereto that have respective bearing surfaces 908. The innerrace 902 also includes a plurality of bearing elements 910 affixedthereto that have respective bearing surfaces 912. One or more, or allof the bearing elements 906 and 910 may be configured according to anyof the PDC embodiments disclosed herein. The inner race 902 ispositioned generally within the outer race 904, with the inner race 902and outer race 904 configured so that the bearing surfaces 908 and 912may at least partially contact one another and move relative to eachother as the inner race 902 and outer race 904 rotate relative to eachother during use.

Although the various embodiments of methods disclosed herein aredirected to employing carbon-saturated sintering aid materials tofacilitate forming PCD materials and structures. In other embodiments,the carbon-saturated sintering aid materials may be replaced with any ofthe sintering aid materials disclosed herein that are at least saturatedwith hexagonal boron nitride via mechanical milling a sintering aidmaterial and hexagonal boron nitride. Cubic boron nitride particles maybe sintered in the presence of the sintering aid material at leastsaturated with hexagonal boron nitride to form polycrystalline cubicboron nitride.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, are open ended and shall have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

What is claimed is:
 1. A method of fabricating a polycrystalline diamondcompact, comprising: providing an at least partially leachedpolycrystalline diamond body including a plurality of bonded diamondgrains exhibiting diamond-to-diamond bonding therebetween and defining aplurality of interstitial regions; forming an assembly including the atleast partially leached polycrystalline diamond body, a substrate, andan at least carbon-saturated infiltrant layer positioned between the atleast partially leached polycrystalline diamond body, the at leastcarbon-saturated infiltrant layer including at least carbon-saturatedmaterial at least saturated with non-diamond carbon; and subjecting theassembly to a high-pressure/high-temperature process effective toinfiltrate at least a portion of the plurality of interstitial regionsof the at least partially leached polycrystalline diamond body with atleast a portion of the at least carbon-saturated material from the atleast carbon-saturated infiltrant layer.
 2. The method of claim 1wherein the at least carbon-saturated material includescarbon-supersaturated material.
 3. The method of claim 1 wherein the atleast carbon-saturated material includes at least one material selectedfrom the group consisting of cobalt, nickel, iron, copper, aluminum,titanium, tungsten, niobium, zirconium, tantalum, silicon, and boron. 4.The method of claim 1 wherein the at least carbon-saturated materialincludes at least one member selected from the group consisting ofcopper particles supersaturated with the non-diamond carbon and nickelparticles supersaturated with the non-diamond carbon.
 5. The method ofclaim 1 wherein the non-diamond carbon is provided from at least onematerial selected from the group consisting of lamp black, graphite,carbon-12 graphite, carbon-13 graphite, carbon nanotubes, graphene,amorphous carbon, and fullerenes.
 6. The method of claim 1 wherein theat least carbon saturated material includes a plurality of at leastcarbon-saturated material particles.
 7. The method of claim 1 whereinthe at least partially leached polycrystalline diamond body is formed bya process including: at least saturating a sintering aid material withnon-diamond carbon to form a carbon-saturated sintering aid material;sintering a plurality of diamond particles in the presence of thecarbon-saturated sintering aid material to form a polycrystallinediamond body; at least partially leaching the sintering aid materialfrom the polycrystalline diamond body to form the at least partiallyleached polycrystalline diamond body.
 8. The method of claim 7 whereinthe sintering aid material includes a plurality of sintering aidparticles, and wherein at least saturating a sintering aid material withnon-diamond carbon to form a carbon-saturated sintering aid includessupersaturating the plurality of sintering aid particles with thenon-diamond carbon.
 9. The method of claim 8 wherein the plurality ofsintering aid particles includes at least one material selected from thegroup consisting of cobalt, nickel, iron, copper, aluminum, titanium,tungsten, niobium, zirconium, tantalum, silicon, and boron.
 10. Themethod of claim 7, further comprising: wherein the carbon-saturatedsintering aid material includes carbon-saturated sintering aidparticles; mixing the carbon-saturated sintering aid particles with theplurality of diamond particles to form a mixture; wherein sintering aplurality of diamond particles in the presence of the carbon-saturatedsintering aid material to form a polycrystalline diamond table includessubjecting the mixture to a high-pressure/high-temperature processeffective to form the polycrystalline diamond body.
 11. The method ofclaim 7 wherein at least saturating a sintering aid material withnon-diamond carbon to form a carbon-saturated sintering aid materialincludes mechanically milling the non-diamond carbon and the sinteringaid material together to form the carbon-saturated sintering aidparticles.
 12. The method of claim 1 wherein the substrate includes acemented carbide substrate.
 13. The method of claim 1, prior to the actof subjecting the assembly to a high-pressure/high-temperature process,further comprising removing at least some leaching by-products from theat least partially leached polycrystalline diamond body.
 14. The methodof claim 1 wherein subjecting the assembly to ahigh-pressure/high-temperature process effective to infiltrate at leasta portion of the plurality of interstitial regions of the at leastpartially leached polycrystalline diamond body with at least a portionof the at least carbon-saturated material from the at leastcarbon-saturated infiltrant layer includes infiltrating a portion of theplurality of interstitial regions of the at least partially leachedpolycrystalline diamond body adjacent to the substrate with a metallicinfiltrant from the substrate.
 15. The method of claim 14 wherein themetallic infiltrant includes at least one of cobalt, iron, or nickel.16. A method of fabricating a polycrystalline diamond compact,comprising: providing an at least partially leached polycrystallinediamond body including a plurality of bonded diamond grains exhibitingdiamond-to-diamond bonding therebetween and defining a plurality ofinterstitial regions; forming an assembly including the at leastpartially leached polycrystalline diamond body, a cobalt-cementedtungsten carbide substrate including a cobalt cementing constituent, andan at least carbon-saturated infiltrant material positioned between theat least partially leached polycrystalline diamond body, the at leastcarbon-saturated infiltrant material including at least carbon-saturatedmaterial at least saturated with non-diamond carbon; and subjecting theassembly to a high-pressure/high-temperature process effective toinfiltrate a portion of the plurality of interstitial regions of the atleast partially leached polycrystalline diamond body with at least aportion of the at least carbon-saturated material from the at leastcarbon-saturated infiltrant material and a portion of the plurality ofinterstitial regions of the at least partially leached polycrystallinediamond body adjacent to the substrate with a portion of the cobaltcementing constituent from the cobalt-cemented tungsten carbidesubstrate.
 17. The method of claim 16 wherein the at leastcarbon-saturated material includes carbon-supersaturated material. 18.The method of claim 16 wherein the at least carbon-saturated materialincludes at least one material selected from the group consisting ofcobalt, nickel, iron, copper, aluminum, titanium, tungsten, niobium,zirconium, tantalum, silicon, and boron.
 19. The method of claim 16wherein the at least carbon-saturated material includes at least onemember selected from the group consisting of copper particlessupersaturated with the non-diamond carbon and nickel particlessupersaturated with the non-diamond carbon.
 20. A method of fabricatinga polycrystalline diamond compact, comprising: mechanically milling asintering aid material with non-diamond carbon to form an at leastcarbon-saturated sintering aid material, wherein the non-diamond carbonincludes at least one material selected from the group consisting oflamp black, graphite, carbon-12 graphite, carbon-13 graphite, carbonnanotubes, graphene, amorphous carbon, and fullerenes; sintering aplurality of diamond particles in the presence of the at leastcarbon-saturated sintering aid material to form a polycrystallinediamond body; at least partially leaching the sintering aid materialfrom the polycrystalline diamond body to form an at least partiallyleached polycrystalline diamond body including a plurality of bondeddiamond grains exhibiting diamond-to-diamond bonding therebetween anddefining a plurality of interstitial regions; forming an assemblyincluding the at least partially leached polycrystalline diamond body, acobalt-cemented tungsten carbide substrate including a cobalt cementingconstituent therein, and an at least carbon-saturated infiltrantmaterial positioned between the at least partially leachedpolycrystalline diamond body, the at least carbon-saturated infiltrantmaterial including at least carbon-saturated material at least saturatedwith non-diamond carbon; and subjecting the assembly to ahigh-pressure/high-temperature process effective to infiltrate a portionof the plurality of interstitial regions of the at least partiallyleached polycrystalline diamond body with at least a portion of the atleast carbon-saturated material from the at least carbon-saturatedinfiltrant material and a portion of the plurality of interstitialregions of the at least partially leached polycrystalline diamond bodyadjacent to the substrate with a portion of the cobalt cementingconstituent from the cobalt-cemented tungsten carbide substrate.